local function queue()
  local out = {}
  local first, last = 0, -1
  out.push = function(item)
    last = last + 1
    out[last] = item
  end
  out.pop = function()
    if first <= last then
      local value = out[first]
      out[first] = nil
      first = first + 1
      return value
    end
  end
  out.iterator = function()
    return function()
      return out.pop()
    end
  end
  setmetatable(out, {
    __len = function()
      return (last-first+1)
    end,
  })
  return out
end

local q1 = queue()
-- Place a few elements into queue
for _, element in ipairs {'Lorem','ipsum','dolor','sit','amet'} do
  q1.push(element)
end

-- You can use iterator to process all elements in single for loop
for element in q1.iterator() do
  -- each queue element will be printed onto screen
  print(element)
end
